This invention relates generally to couplings for electrical conduits or the like. More particularly, this invention relates to an improved swivel coupling and mating conduit as well as the method for assembling same which provides for a temporary locking connection therebetween to aid in the connection thereof to another conduit.
In attaching a coupling member to an electrical conduit containing electrical conductors, the coupling member must be threaded tightly but not too tightly or the threads would strip. It is also a common requirement of the coupling means of the type to which the present invention is directed that a seal be provided since in many environments liquids may be splashed on the conductors and, additionally, moisture in the air could enter the conduit via the smallest opening in the coupling and be condensed and trapped in the threads therein thus enhancing corrosion and poor electrical connections. Liquid that is present in the conduit could possible short out the conductors.
There are many examples of prior art in the general field to which the present invention is directed. One such example which provides a temporary locking arrangement is disclosed in the U.S. patent application Ser. No. 669,444 filed on Mar. 23, 1976, and assigned to the assignee of the present invention. In the aforementioned, co-pending application, the coupling is comprised of an elongated sleeve having internal threads at one end thereof. The opposite end of the sleeve is deformable and is initially flared outwardly. A radially inwardly extending lip is formed integrally with one end of the deformable section and is adapted to engage an annular groove formed on the exterior surface of a length of conduit. When the external groove is formed on the conduit, it will be evident that conventional threads are not required at that end. The opposite end of the coupling is threaded in a conventional manner so as to receive the theaded end of the conduit and an annular seal ring may be provided between the confronting ends of the two members that are to be joined.
While the copending application referred to hereinabove does overcome many swiveling problems present in the prior art, it will be evident that the construction requires the absence of threads at one end of the conduit, even though swiveling is required and is achieved. The temporary locking of one conduit to another is achieved by means other than threads. As will be made evident from the discussion that follows, the present invention provides a fully threaded, swivel coupling between adjacent conduit ends.